Many types of switch mechanisms are utilized in residential, commercial, industrial and military applications. A particular application of switch mechanisms of this type relate to pushbutton switches that comprise a plunger that is movable relative to a base along an axis and which causes actuation of switching components when the plunger is depressed. Typically, the plunger is connected to a button that is depressible by a human finger. Some switch mechanisms cause actuation of a switch upon each depression of the button and plunger while other switch applications, referred to as alternate action devices, actuate on one push and release of the button and undo the actuation on a subsequent push and release of the button.
Generally, a plunger switch is mounted to an electric appliance to control a lamp, a motor, a heater and so forth. Due to external pressure generated by electrical and mechanical elements, a point of contact of the plunger switch engages the electric appliance. Meanwhile, when the external pressure is eliminated, the contact of the plunger switch returns to an original position thereof, thus maintaining an operable position.
In many switch designs and other mechanically actuated devices, the plunger is utilized as the input mechanism to force some other action within the surrounding enclosure (i.e., case or housing). Plungers come in all different shapes and sizes but are usually retained in their respective enclosures by similar means. In most cases, a spring or similar feature can provide resistance to the actual movement of the plunger within the enclosure.
Many electrical switches are of the type which encounter “overtravel” after the state of the electrical connection of the switch has been altered. In most instances, an actuator is employed to operate the switch. The actuator and its associated components usually go through a “pretravel” before electrical connection is made or the switch state is altered, which sometimes is termed the “operating point”. The actuator and/or its associated components go through an overtravel condition of movement after the operating point. Upon release of the actuator, reverse movement usually takes place and a “release point” occurs when the electrical connection and its associated circuit is transferred back to its original state. This usually occurs sometime during return movement of the actuator.
Plunger switch design inherently requires that actuating plunger travel must be the same as the return plunger travel plus movement differential before the switch can transfer the circuit to the original position. It further means that the actuation device and/or the switch mounting method must be designed to accommodate manufacturing tolerances in the involved apparatus components and still provide sufficient movement so that plunger travel through the operating point into the overtravel region will ensure that the switch can change states each time it is actuated. In many instances the attainment of these relations is complicated by the fact that normal manufacturing tolerances alone can be greater than the total travel (return plunger travel plus movement differential plus maximum permitted overtravel) of the switch thereby requiring the use of expensive and complicated mounting bracketry.
Based on the foregoing it is believed that a need exists for an improved sealed switch assembly that can receive actuation inputs at two different plunger locations. Additionally, a need exists for achieving the desired operating point of each plunger in a way such that they operate simultaneously within a fixed distance from the assembly's mounting surface.